onan fuel pump replacement

OK' on our last trip after running our Onan 5500 gen. for a while ( 6 to 8 hours) we started to hear a clicking coming from the gen. a few minutes later it shut down. let it sit for a few hours restarted it ran for 30 minutes shut down again. we finished the weekend on batteries... Got it home ran it till it started making noise put my hand on fuel pump it felt like a grimlin with a ballpen hammer was in side.. First thought was pump might be sucking air , pulled the tank cleaned it ( fairly dirty ) pulled fuel through lines with remote pump ( both directions) line was clear,as was pick/up line in tank. All connections were tight before removing tank..Ok so here is my guestion I feel pretty sure its the pump, the pump fron Onan is around $100.00 , a buddy tells me that I can put any 12 volt low preasure pump on it for half the money and it will work good as new. has anyone done this with any luck.. or does anyone have any knowledge on the specs for the factory pump(psi- gph) so i can narrow down a better replacement than the china c--p onan sells.. As a side note the gen has a filter before and after the pump that i will be replacing with premium inline filters getting rid of those cheap china filters..

I just replaced a fuel pump on an Onan I am rebuilding to sell with a low pressure pump (also made by Facet) that I picked up at NAPA for about $48. The OEM pump for my Onan genset was almost $200. The NAPA pump works prefect. I did have to drill and tap a couple new holes for the mount and rework the fuel line a little to get everything to fit right.

But first, I would disconnect the fuel line at the carb and place the end of the line into a small container and see if it is pumping fuel. My experience with these pumps is that when you hear the clicking you are pumping air, not fuel. It sounds like the pump is pumping, just not moving fuel. Maybe your fuel line has some small cracks in it or your hose clamps are loose (although I would think you would see some leaking fuel if that were the case). There is also a chance you have an obstruction at the pump inlet.

I should add that I have been admonished on this forum a couple of times before when I gave fuel pump trouble shooting advice. So I'll add that when you are working on a fuel pump and disconnecting lines there is a potential for fire. If you are not comfortable performing these repairs, seek a professional mechanic.

Be safe,
John

I don't know what brand fuel pump your Onan has... but, I had one on my last boat and it had a Bendix brand pump. On the bottom of this pump was a fuel filter. By turning the bottom of the (round) pump I could get to the filter for cleaning. I would make sure you do not have any other filters in the fuel line. You stated your tank was dirty, then the filters (if any) between the tank and genny may need attention. Disclaimer : If you are not comfortable doing this perhaps a Onan tech should be called, they have mobile service. Tom

Not to add much on the topic but to emphasize the safety aspect - do be careful.
Our local Memorial Day parade was a bit shorter this year as all the volunteer fire companies left in the middle. I was told it was first called as a vehicle fire, then called as a structure fire, then called as a "y'all get over here".

Apparently someone working on a truck parked next to a building... the truck was a total loss and the building pretty bad.

Sounds like you have done a bit of tank and line cleaning already. Pull the fuel line off the carb and turn the switch on to see if it pumps. Let it pump several gallons through if it works. The clicking is normal as mine does and also the pump on my diesel sailboat that I replaced with a NAPA and keep a spare on board. If not pumping I assume you have blown backward though the lines (with fueling cap off). Keep us informed.